A significant cause of mortality after unrelated umbilical cord blood transplant (UCBT) is due to recurrence of the underlying malignancy. While infusion of tumor-specific T cells is a conceptually attractive strategy to enhancing graft-versus-leukemia (GVL)-effect and reducing relapse rates for patients undergoing allogeneic transplant with marrow- or peripheral blood-derived hematopoietic progenitor cells, the anonymity of the umbilical cord blood (UCB) donor has so far precluded this application of adoptive immunotherapy after UCBT. To overcome this limitation, we have generated T cells from UCB that are specific for CD19, a molecule commonly expressed on B-lineage leukemias and lymphomas. The specificity for CD19 is derived from a chimeric immunoreceptor expressed on the cell surface of genetically modified T cells that combines antibody-recognition of CD19 with the effector-function of T cells activated through chimeric CD3-?. This grant proposes to enhance the therapeutic potential of these UCB-derived CD19-specific T cells by evaluating three approaches to improving their in vivo persistence, and therefore anti-tumor effect, after adoptive transfer. (1) Ex vivo-expanded genetically manipulated CD8+ T cells are dependent in vivo on T-cell help, which can be provided by exogenous IL-2, to sustain proliferation and survival. Therefore, CD19-specific T cells will be combined with CD10-specific-IL2 immunocytokine (ICK) in order to coordinate delivery of a T-helper (Th) response at sites of CD10-binding in the microenvironment of CD19+CD10+ B-lineage malignancies. (2) Genetically modified CD19-specific CD4+ T cells are a potential source of antigen-specific help. Therefore, UCB-derived CD4+ T cells will be evaluated as a source of Th activity for CD8+ CD19- specific T cells. (3) Fully-competent activation of T cells resulting in their proliferation and survival requires coordinated signaling through both an antigen receptor and secondary co-stimulator molecules. Therefore, the CD19-specific chimeric immunoreceptor will be modified to provide genetically modified CD4+ and CD8+ T cells, with tandem activation and co-stimulation through CD28, upon engagement with B7-CD19+ malignant targets. These data will facilitate the design of clinical protocols using adoptive immunotherapy to enhance the GVL-effect, not just after UCBT, but also after allogeneic hematopoietic stem-cell transplants in general. Lay language: Infusing tumor-specific T cells derived from cord blood may reduce relapse rates after umbilical cord blood transplant. This grant therefore proposes to generate tumor specific T cells from cord blood and evaluate their potential for immunotherapy.